Swift 1.5 Qwen3.8-27B W4A16 (AutoRound, BF16 MTP head)

A community 4-bit weight-only quantization of ukisai/Swift-1.5-Qwen3.8-27b, UkisAI's reasoning-efficient fine-tune of Qwen3.8-27B. It is not an official UkisAI release; UkisAI's own quantizations are listed on the parent card.

  • W4A16: int4 weights (group size 128, symmetric), 16-bit activations, made with Intel AutoRound 0.15.1 and exported as compressed-tensors. vLLM picks the int4 kernels up automatically (Machete on Hopper, Marlin elsewhere).
  • 19.47 GB on disk versus about 56 GB for the BF16 parent.
  • BF16 MTP head: the multi-token-prediction module is kept at full precision and listed in the quantization ignore list, so self-speculative decoding works as it does on the parent.

Status: not yet evaluated. This checkpoint has not been benchmarked or load-tested in vLLM. It uses the same recipe, layout and toolchain as causal/Swift-Qwen3.8-27b-W4A16-AutoRound-MTP-BF16 (the Swift 1.0 version), which serves in vLLM 0.27.1 and scored within noise of its parent's published numbers on GPQA-Diamond, IFBench and AIME 2026.

Benchmarks

None measured for this repository yet. The parent card reports the following; they are copied here for reference and were not measured on this checkpoint.

Benchmark Swift 1.5 BF16, 5 seeds Swift 1.5 BF16, seed 0 UkisAI AutoRound INT4, seed 0
GPQA-Diamond 88.59% 91.41% 89.39%
IFBench (strict) 72.07% 72.00% 69.33%
AIME 2026 96.00% 86.67% 83.33%
  • 5 seeds: the parent's main table. vLLM 0.27.1, context 262,144, reasoning effort xhigh, AIME capped at 250,000 tokens.
  • Seed 0: the parent's quantized-model comparison. vLLM 0.29.0, context 131,072, template-default thinking, one sample per prompt, AIME capped at 32,768 tokens with truncated answers scored incorrect.
  • The two protocols differ in caps, seeds and serving stack, so compare within a column, not across columns.

Quantization details

Setting Value
Method AutoRound 0.15.1, W4A16, group size 128, symmetric
Quantized 400 Linear layers: GatedDeltaNet in_proj_qkv / in_proj_z / out_proj, all MLP projections, full-attention q/k/v/o
Kept in BF16 vision tower (110 Linear), GatedDeltaNet in_proj_a / in_proj_b (96), lm_head, embeddings, MTP head (8 Linear)
Calibration NeelNanda/pile-10k, 128 samples x 2,048 tokens, 200 iterations, batch 4, seed 42
Export compressed-tensors (pack-quantized)
Toolchain auto-round 0.15.1, transformers 5.17.0, vLLM 0.29.0 image (CUDA 13.0)
Cost 46 min on one NVIDIA L40S, peak 17.4 GB VRAM

The layer selection follows dbirks/Qwen3.8-27B-W4A16-AutoRound, except that the MTP head stays BF16 and is listed in quantization_config.ignore so vLLM builds the draft module unquantized. UkisAI's own AutoRound release uses the auto-round format instead of compressed-tensors.

How to use

vLLM

vllm serve causal/Swift-1.5-Qwen3.8-27b-W4A16-AutoRound \
  --max-model-len 262144 \
  --reasoning-parser qwen3 \
  --enable-auto-tool-choice \
  --tool-call-parser qwen3_coder \
  --port 8000

The Swift 1.0 version, which has the same size and layout, loads in 18.5 GiB of GPU memory and fits one full 262K-token request on a single 48 GB L40S. Lower --max-model-len on smaller GPUs.

Optional MTP decoding

--speculative-config '{"method":"mtp","num_speculative_tokens":3}'

MTP speeds up individual requests at low concurrency. On the Swift 1.0 version it lowered total throughput at high batch sizes.

Sampling

Use the parent's recommended settings: temperature 1.0, top_p 0.95, top_k 20, min_p 0.

License and access

This repository is a quantized derivative of ukisai/Swift-1.5-Qwen3.8-27b and carries the same terms. UkisAI's contribution is licensed under the Swift Open License v1.0; the underlying Qwen3.8-27B is licensed under Apache 2.0. See NOTICE.

Use is free for individuals and organizations with gross annual revenue, including affiliates, of up to US$1,000,000. Above that threshold, commercial use requires a Swift Enterprise License from UkisAI.

Changes from the parent: the model weights were quantized to int4 as described above (model-*.safetensors, model_extra_tensors.safetensors, model.safetensors.index.json); config.json gained a quantization_config and quantization_config.json was added; the other config, tokenizer and processor files were re-saved by transformers 5.17.0 during export; this README replaces the parent's. LICENSE, LICENSE-APACHE-2.0 and NOTICE are the parent's.

Citation

@misc{swift-1.5-qwen3.8-27b,
  title  = {Swift 1.5 Qwen3.8-27B},
  author = {UkisAI},
  year   = {2026},
  url    = {https://huggingface.co/ukisai/Swift-1.5-Qwen3.8-27b}
}

Acknowledgements

Swift 1.5 was developed by UkisAI with compute from the NVIDIA Innovation Lab, Amazon Web Services and Google Cloud. Quantization for this repository ran on a Modal L40S.

Downloads last month
25
Safetensors
Model size
6B params
Tensor type
I32
·
BF16
·
Inference Providers NEW
This model isn't deployed by any Inference Provider. 🙋 Ask for provider support

Model tree for causal/Swift-1.5-Qwen3.8-27b-W4A16-AutoRound

Base model

Qwen/Qwen3.8-27B
Quantized
(52)
this model